It has been proposed to provide filter units for textile machines which contain two filter chambers (German open application DE-OS No. 30 10 011) which can be connected selectively to the intake pipe by respective flap valves and which can have flap valves at their outlets for selective communication with the intake side of a blower or with an air-evacuation pipe or passage. The sets of flaps can be provided with common actuators.
This construction allows one of the compartments to be used to filter fibers, fluff and other solids entrained by the air from the latter upon the opening of the flaps associated with that compartment while the other compartment is closed off for cleaning.
In practice this arrangement does not preclude a filter surface which is in the closed-off compartment from accumulating contaminants. Another drawback of the earlier system is that it is relatively complex in construction and requires considerable maintenance.